key term - Parathyroid Hormone

Definition

Parathyroid hormone (PTH) is a polypeptide hormone produced by the parathyroid glands that plays a crucial role in maintaining calcium homeostasis within the body. It is a key regulator of bone formation and development, as well as the interactions between the skeletal system and other organ systems, particularly the endocrine system.

5 Must Know Facts For Your Next Test

1. Parathyroid hormone increases the concentration of calcium in the blood by stimulating the release of calcium from bone, increasing calcium absorption in the intestines, and decreasing calcium excretion by the kidneys.
2. PTH plays a crucial role in bone formation and development by regulating the activity of osteoblasts (bone-forming cells) and osteoclasts (bone-resorbing cells).
3. The parathyroid glands secrete PTH in response to low blood calcium levels, which helps maintain calcium homeostasis.
4. Chronic overproduction of PTH, as seen in hyperparathyroidism, can lead to excessive bone resorption and increased risk of fractures.
5. PTH also influences the regulation of fluid volume and composition by affecting calcium and phosphate levels, which are essential for maintaining proper fluid balance.

Review Questions

• Explain how parathyroid hormone (PTH) contributes to bone formation and development.
  • Parathyroid hormone (PTH) plays a crucial role in bone formation and development by regulating the activity of osteoblasts (bone-forming cells) and osteoclasts (bone-resorbing cells). PTH stimulates osteoclasts to break down bone, releasing calcium into the bloodstream, while also promoting the activity of osteoblasts to build new bone tissue. This dynamic balance between bone formation and resorption is essential for maintaining healthy bone structure and mineral homeostasis.
• Describe the relationship between parathyroid hormone (PTH) and calcium homeostasis.
  • Parathyroid hormone (PTH) is a key regulator of calcium homeostasis, the physiological process of maintaining a stable concentration of calcium in the blood and extracellular fluids. PTH increases the concentration of calcium in the blood by stimulating the release of calcium from bone, increasing calcium absorption in the intestines, and decreasing calcium excretion by the kidneys. The parathyroid glands secrete PTH in response to low blood calcium levels, which helps restore calcium balance and maintain proper nerve and muscle function, as well as bone health.
• Analyze the role of parathyroid hormone (PTH) in the interactions between the skeletal system and other organ systems, particularly the endocrine system.
  • Parathyroid hormone (PTH) plays a central role in the interactions between the skeletal system and other organ systems, particularly the endocrine system. PTH regulates calcium homeostasis, which is essential for proper nerve and muscle function, as well as bone health. PTH influences the activity of osteoblasts and osteoclasts, thereby affecting bone formation and resorption. Additionally, PTH interacts with other endocrine hormones, such as calcitonin from the thyroid gland, to maintain calcium balance. This intricate interplay between the skeletal system and the endocrine system, mediated by PTH, is crucial for overall physiological homeostasis and development.

Related terms

Calcium Homeostasis:

The physiological process of maintaining a stable concentration of calcium in the blood and extracellular fluids, which is essential for proper nerve and muscle function, as well as bone health.

Osteoclasts:

Specialized cells that break down and resorb bone tissue, releasing calcium into the bloodstream, which is a key function regulated by parathyroid hormone.

Calcitonin:

A hormone produced by the thyroid gland that opposes the effects of parathyroid hormone, helping to lower blood calcium levels.